NORTHAMPTON — It was the early 1970s and a Valley band called The Deadly Nightshade was playing a gig in Bernardston when bassist Pamela Robin Brandt looked out across bodies on the dance floor. She spotted people in square dance gear and cowboy boots kicking up their heels.

Near them, Brandt recalled Friday, danced men in beards who defined themselves as “radical fairies.” Circling the floor, hands joined, was a cadre of gay women from Smith College. Two of the band members were Smithies; Brandt had graduated from Mount Holyoke in 1969.

“I was just looking out and it was so weird to see all of those people not fighting, and thought, ‘This is a microcosm of the world I’d like to live in,’ ” said Brandt, whose band returns to the Valley Sunday for a rare performance of its blend of rock, country and bluegrass. “The Pioneer Valley is still one of the weirdest places on Earth — in a good way. They not only tolerate weirdness, but actively welcome it.”

It has been four decades since The Deadly Nightshade traded local stages with bands like Fat and Clean Living and went on to score a major label deal with RCA that resulted in albums in 1975 and 1976.

The 1970s were a high point for Brandt and her bandmates, Anne Bowen and Helen Hooke. The group toured with Billy Joel, opened for Peter Frampton and performed on “Sesame Street,” even writing songs for that show. The trio created a single inspired by the TV show “Mary Hartman, Mary Hartman” that made it to No. 67 on national charts. They performed on a Hudson River ferry to celebrate the second anniversary of Ms. magazine.

And then, like a lot of bands, the fuse burned out. Bowen wanted more personal time after all the touring and Brandt said she and Hooke felt The Deadly Nightshade was done.

“We never had a leader. We each contributed what we were best at. The band could not go on without any one of us,” Brandt said.

The Deadly Nightshade’s music lives on through the Country Music Hall of Fame and is archived at the Smithsonian.

“All-female bands have never been a routine part of the rock and pop landscape,” said Steve Waksman, a professor of music and American studies at Smith College.

The Deadly Nightshade, Waksman said, was a band “that represented the moment where a little space opened up for women.”

After breaking up, members went on to other lives and day jobs in Arizona, Florida and New York, but got back together for a show in Goshen in 2008 and followed that with one in Northampton in 2009. Though all now in their mid-60s, the members rallied after those performances to record a CD called “Never Never Gonna Stop.”

They plan to perform songs from it Sunday at the Iron Horse, mixing in songs like “High Flying Woman” from their early days as well as covers their audiences always liked, such as “Teach Your Children” by Crosby, Stills, Nash and Young and maybe “Truckin’” by the Grateful Dead. The 7 p.m. show opens with a set by singer-songwriter Kristen Ford.

This past week, Brandt, Hooke and Bowen practiced in spaces on Long Island and in New York City. But Brandt said that even when they reunited five years ago — after decades apart — it was a breeze to reconnect.

In the old days, The Deadly Nightshade liked to start sets with the 1899 American song “Keep on the Sunny Side,” but with a decidedly up tempo. Brandt said she and her bandmates kicked right into it. “It sounded just like it had before, just like 30 years before. We had to stop because we were laughing so hard.”

They moved through their long-ago song list, practicing in a Brooklyn apartment in a quiet, cobblestone-lined area. If they worried about making too much noise, they shouldn’t have.

“All of the neighbors, when we came out after practicing, they’d all clap,” Brandt said.

Now that she’s 66, Brandt really likes to crank it up. She jokes that older women need more watts. “I’ve just gotten bigger and bigger amplifiers. ... I really have lost some of that ambient hearing thing.”

While Bowen largely left music, Brandt continued to play bass while working day jobs as a newspaper and magazine freelancer, now from her base in Miami.

When the band reunited in 2008, it played at the Institute for the Musical Arts in Goshen, managed in part by June Millington, formerly of the all-women band Fanny. Today, The Deadly Nightshade’s albums in the 1970s stand out as an advance for women in music.

The IMA show in Goshen drew an overflow crowd of nearly 150 and convinced the band it still had a local following.

A 1974 New York Times “Pop Life” column by John Rockwell noted that The Deadly Nightshade members had described themselves as “an all-girl band before we knew what that meant.”

Today, Brandt knows how it all sifted out. She said the band resisted being labeled a feminist act for a reason. “It was actually our feminist statement,” she said. “RCA had said, ‘Why can’t you girls do more normal songs, regular songs’ ... which meant sexist songs. The Rolling Stones could sing sexist songs, but if we sang feminist songs, it was political.”

“Bands are bands, and we didn’t want to be the women’s band or the feminist band. ... We wanted to be a band like all of the guy bands,” she said.

Waksman, the Smith professor, said it made sense for the band to want recognition for the music alone. “That’s been a strategy that female musicians have used often,” he said. He notes that Millington, of Fanny, eventually moved away from rock and toward another category. “Women’s music gave her a community that rock and roll didn’t.”

In time, the emergence of popular women musicians threw questions of gender aside. “All of those women’s bands, collectively, had an effect,” Brandt said. “I have no idea how much effect we had on any woman who later turned out to play.”

In his 1974 writeup, Rockwell seemed to struggle to balance the folky appeal of the band’s music — it used a washboard and kazoos for percussion — against the implicit feminism of an all-female group.

He may have been thrown by the band’s name, taken from a toxic plant long used as both a medicine and a poison.

Rockwell noted Brandt’s “slinky sexuality.”

Reminded of that line Friday, Brandt laughed. “I’m really kind of a nerd. I didn’t quite connect with what he was talking about.”